1. Field of Invention
The invention relates to a light module for motor vehicle headlights.
2. Description of the Related Art
In the present context, a light module is understood to be the actual light emitting unit that delivers the desired light beam distribution. This light module can be installed in a motor vehicle headlight, e.g. incorporated in a headlight housing. Depending on the field of application, the light beam distribution should exhibit certain, frequently government regulated, characteristic intensity distributions.
On the one hand, it is of interest to generate a dimmed light distribution, distinguished by a light/dark border that is substantially horizontal in sections. This light distribution exhibits a dark region vertically above the border, and a light region vertically below the border, wherein the light region is separated from the dark region by the light/dark border. For this, the brightest possible illumination is desired in the region directly beneath the light/dark border (low beam/spot light distribution), in order to obtain a sufficient range. Moreover, a sufficient illumination of the region in front of the vehicle or the regions to the side should be ensured (base-light light distribution). Light modules of this type can be used as low beams or fog lights.
Moreover, frequently a high beam light distribution is to be generated with motor vehicle headlights, exhibiting a high level of illumination in a region above the light/dark border (i.e. in the dark region of the low beam light distribution). The high beam distribution should be superimposed over the base-light distribution of the low beam light distribution in a manner that is homogenous to the greatest extent possible. By way of example, a disruptive stripe pattern in the transition between the different light distributions, particularly in the light/dark border, should be prevented.
Depending on the field of application, other light functions such as daytime running lights, demarcation lights, or signal lights should be provided. For this, usually a large portion of the light emitting surface of the light module should exhibit a spatially constant light density, in order to obtain the appearance of homogeneity to the greatest extent possible.
In order to implement the various light beam distributions, projection systems, on one hand, are known. These are usually two-step optical systems, in which light from a light source is deflected by a primary lens to the focal plane of a secondary lens, which projects light with the desired emitted light distribution. Due to the two-step structure, projection systems normally require a large assembly space along the beam path. Aside from this, reflection systems are known, in which a reflector is used to shape and deflect the light emitted from a light source into the emitted light distribution. For this, reflector surfaces that have a complex shape and are large are usually necessary in order to obtain the desired light distribution.
The use of LEDs is frequently desired as the light source for motor vehicle headlights, because these exhibit a comparatively low power consumption and a comparatively high efficiency in terms of power conversion. However, LEDs usually generate a lower luminous flux than gas discharge lamps or halogen lamps. For this reason, more LED light sources must be combined to form a light module in order to generate a sufficiently high luminous flux.
A light module of the type known in the related art is described in published US Pat. Application No. 2009/0091944 A1. In this case, the disk-like light conducting sections converge in the region of their light coupling surfaces. This can lead to problems regarding the exhaust heat of the semiconductor light sources allocated to the respective light coupling surfaces, because these are disposed in close proximity to one another. With the light module described therein, each light conducting section also exhibits a massive, cylindrical lens-type end piece at its light decoupling surface, which extends along the respective light decoupling surface. Due to the size of these end pieces, the light conducting sections must maintain a minimum spacing to one another in the region of their light decoupling surfaces. The light module thus has a comparably large light emitting section. Furthermore, there is a significant expenditure in terms of materials.
The objective of the invention is to eliminate the specified disadvantages of the known light module. In particular, a compact light module having semiconductor light sources is to be provided, which exhibits a high level of optical efficiency and which enables the generation of different light beam distributions with a single module.